The game started development in 1997, using the Quake 2 game engine. After missing an unofficial late-1998 release date (the company has always claimed "When It's Done" as an official release date), the company decided to restart the production of the game with the Unreal engine. Since then the game switched publishers, engines, and release dates multiple times, until it was finally released in 2011. The game now holds the record for the longest time a single video game has spent in development, clocking in at 14 years.
When Duke awakes in his strip club after being knocked out in the Duke Dome, if the player is uncertain if he is imagining being there or is actually there they can confirm that he is still unconscious by going to the room with the security terminal ("Exit - Employees only" door easy to find) by the terminal on the desk is a constantly spinning-top a reference to Inception (2010). In that movie Leonardo DiCaprio's character uses a spinning-top to confirm if he is still dreaming as in dreams it constantly spins.
The first sign that Duke is still unconscious when he's at his strip club and a reference to Portal (2007) is that the lap dancer at the beginning of the level promises a lap dance and cake for completing a task. In Portal (2007), cake is promised for completing a series of tasks. It's only later revealed by writings on the walls that "the cake is a lie."
According to an Internet post made by a senior designer, all work done before 2003, minus textures, has been scrapped and is in the process of being redone. Since then, the designer has confirmed that the texture work is also being redone.
This is the first Duke Nukem video game where Duke is known to use the word "fuck" and "motherfucker" throughout his quotes and dialogues.